A metal rod of resistance $20 \;\Omega$ is fixed along the diameter of a conducting ring of radius$0.1 m$ . A magnetic field of $B=50T$ acts perpendicular to the plane The ring rotates with an angular velocity of $w=20\;rad/s$ about its axis . An external resistance of $10 \;\Omega$ is connected across center and rim of the ring. What is current through the external resistance.